Personal financial data of several US celebrities and politicians, including First Lady Michelle Obama, have been posted on the internet by hackers, US authorities have said.

On Tuesday, the Federal Bureau of Investigation (FBI) said that it was investigating a website which used a Russian web address to publish financial and personal information which it claimed to belong to 18 prominent US public figures.

The hackers published social security numbers, telephone numbers, addresses and credit reports of prominent people such as Joe Biden, the vice president and Hillary Clinton, the former secretary of state.

Three leading personal credit-monitoring agencies, Transunion, Equifax and CreditKarma, acknowledged the files were accessed illegally, but said it was done through other firms by someone using the personal data of the victims, and not by hacking their own computers.

The Secret Service and the Los Angeles Police Department has said that they are also investigating the matter.